The Giant arts and graphs are great! Having now ridden all three wheel sizes, I will say 650b will keep my Mojo HD around for a lot longer. However, their silly science doesn't exactly compute on the trail, at least for me. Yup I felt the 650 wheels were a bit smoother over the low lever chatter, but seriously, they need to move that 27.5 closer to the 26 on their graph, not right beside the 29er. My 29er is far and away smoother over the roots and rocks, a LOT more noticeable between the 29 and 650b than they might let on.
So which company's engineers are on the pipe? Giant claims a huge advantage (the graphs!), while Specialized claimed no discernible advantage, and Santa Cruz was just fuck it we'll give the dudes with the cash what they want.